My invention comprises a circuit particularly useful for controlling the speed of DC motors and other DC powered devices in all applications. The circuit is described herein with respect to its use on a trolling motor for fishing boats although it should be understood that the utility of the invention is not limited to this narrow application.
Prior art DC trolling motors have suffered from a number of disadvantages which are obviated by the circuit of my invention. In the past if the motor was forcibly stopped by weeds or the like a hazard was created in that as soon as the weeds were cleared as, for example, by hand, the motor would start again very quickly often injuring the person who was clearing the obstruction. My circuit avoids this problem by automatically shutting down the current to the motor and keeping the current off until the throttle is manually cycled to zero and back up again. Accordingly, if the operator forgets to move the throttle to zero there is still no hazard created when the obstruction is cleared and the motor freed.
Another problem common to prior art trolling motors involves inefficiency in the circuit in which much of the battery power that should be conserved for running the motor is lost as heat in the control circuits. The present invention minimizes this aspect too as described below.